The present invention relates to devices for installing resin set bolts into the ceiling and walls of a mine, and more particularly for a device for positioning a resin nozzle for injecting a resin sausage into a pre-drilled bolt hole.
Rock bolts and associated bolt plates are used in underground structures such as mines to reinforce the rock. These rock bolts are installed by a rock bolter having a drill, which bores a bolt hole along a work axis, and a bolt driver, which places a bolt into the hole after the bolt has been brought to the work axis. When the bolt is to be held in place by resin, the rock bolter drills the bolt hole and thereafter a resin sausage is placed into the bolt hole. The casing of the resin sausage is broken by inserting a bolt into the bolt hole, and the resin from the sausage forms a bond between the bolt and the rock. To avoid premature breakage of the resin sausage, it is necessary to align the resin sausage with the hole prior to inserting it. While such alignment can be performed manually, such requires providing an operator access to the site of the hole, which can present safety risks and/or can delay the bolt setting operation. Thus, it is preferred to provide a resin nozzle having a nozzle axis in combination with a mechanism which can move the resin nozzle to align the nozzle axis with the work axis, thus aligning a nozzle passage of the resin nozzle, through which the resin sausage passes, with the bolt hole to guide the resin sausage thereinto. In some cases, a centralizer is provided on the rock bolter to guide the drill and thus define the location of the bolt hole. When a centralizer is provided, the nozzle passage need only be aligned with a centralizer passage of the centralizer, and the centralizer can serve to direct the resin sausage into the bolt hole. To insert the resin sausage, the resin nozzle must be moved into alignment with the bolt hole after the hole has been bored by the drill. After insertion, the resin nozzle must then be moved away from the hole to allow the bolt driver to advance the bolt into the hole. Thus, the resin nozzle must be moved reliably to and from a position where it is aligned with the bolt hole to guide the resin sausage therein.
One approach to the problem of positioning the resin nozzle for single feed track rock bolters is a device by J. H. Fletcher and Co., Inc. which uses a carousel for storage of a number of resin sausages. The resin nozzle is provided at one end of the carousel, and the resin sausages are sequentially rotated into alignment with the resin nozzle. When a resin sausage is so aligned, it is also aligned with a flexible extendable pusher which serves to push the resin sausage through the resin nozzle. The carousel is mounted to a frame of the rock bolter by a link, which is pivotably connected to both a top region of the carousel and to the frame so as to be disposed substantially parallel to a longitudinal nozzle axis of the resin nozzle, and by an arm, which is pivotably connected to a base region of the carousel and to the frame at a substantial inclination to the nozzle axis. The pivotable connection provided by the link and the arm allows the carousel to be moved by an actuator into a position in close proximity to the frame, or a position somewhat spaced apart from the frame to provide clearance for the advancement of the drill and the bolt driver. Thereafter, when the carousel is positioned in close proximity to the frame, it is pivoted about an axis parallel to the nozzle axis to bring the nozzle axis into substantial alignment with the work axis. The multiple actions make accurate alignment between the nozzle axis and the work axis difficult and may inhibit use of the device with some types of centralizers. In addition to requiring complex motion, the Fletcher device is both bulky and heavy, difficult to fabricate, and provides only very limited displacement of the resin nozzle. Additional problems are associated with the pusher for moving the resin sausages through the resin nozzle into the bolt hole.
An alternative approach to inserting resin sausages simplifies the introduction of the resin sausages into the resin nozzle and avoids some of the deficiencies of the Fletcher device by placing each resin sausage into a resin sausage insertion chamber that communicates with a flexible resin hose, which in turn communicates with the nozzle passage of the resin nozzle. The resin nozzle is aligned with the bolt hole and the resin sausage is passed into and through the resin hose and is directed into the bolt hole by the resin nozzle. Further discussion of the injection of resin sausages is found in U.S. Pat. No. 5,494,380, assigned to the assignee of the present application. While this system simplifies the introduction and advancement of the resin sausage through the resin nozzle, the system does not in and of itself offer a solution to the problem of positioning the resin nozzle.
The positioning of the resin nozzle for rock bolters which employ a single feed track has been addressed in U.S. Pat. No. 5,690,449, assigned to the assignee of the present application, which provides a solution when the feed track can be employed to guide a carriage on which the resin nozzle is advanced. Because the resin nozzle is advanced along the work axis, the device can be readily employed with a centralizer to guide the resin nozzle into alignment with the bolt hole. However, this approach places undesirable limits on the sizes of tool bases employed to mount the drill, the resin nozzle, and the bolt driver to the carriage for advancement along the feed track.
Thus, there is a need for a resin nozzle positioning device which does not require the use of a feed track, has a simple structure, and provides a large displacement of the resin nozzle to assure that the resin nozzle and related components do not interfere with the drilling or bolt setting apparatus. Furthermore, there is a need for a resin nozzle positioner which moves the resin nozzle onto the work axis with a substantial component of the motion being parallel to the work axis to facilitate the use of a centralizer to guide the resin nozzle.
The present invention provides a resin nozzle positioner for use with a rock bolter having a frame which supports one or more feed tracks for the advancement of a drill and a bolt driver along a work axis on which holes are bored and bolts are set into the holes. Preferably, the rock bolter has a centralizer which is also supported by the frame. When a centralizer is employed, it provides guidance and support for a drill rod of the rock bolter when the drill is advanced along the work axis to bore a hole in a rock surface, and thus the centralizer defines the location of the bolt hole. The centralizer can also provide support and guidance of a bolt during the bolt setting operation as the bolt is advanced along the work axis by the bolt driver. When the bolts are to be secured by use of a resin, a resin nozzle guides the insertion of a resin sausage into the hole prior to the setting of the bolt with the bolt driver. To insert the resin sausage into the hole, the resin nozzle is positioned such that the resin sausage is directed along the work axis and is guided into the bolt hole. The use of a centralizer having a centralizer passage with a centralizer axis that is aligned with the work axis simplifies the insertion of the resin sausage, since the resin nozzle need only be brought into registry with the centralizer.
The resin nozzle positioner of the present invention has a positioner base which is mounted so as to be fixable with respect to the frame of the rock bolter. Preferably, to better facilitate the alignment of a nozzle axis of the resin nozzle with the work axis, the positioner base is affixed with respect to the frame or made an integral part thereof.
A pair of arms are pivotably connected to the positioner base. The arms may each be fabricated from single piece of stock or may be fabricated from multiple pieces. When employing multiple pieces, a pair of parallel plates, one connected on either side of the positioner base, can be readily employed to provide an arm with a high strength to weight ratio.
Each arm terminates in an arm base end region and an arm free end region. Each of the base end regions is pivotably connected to the positioner base so as to pivot about a base pivot axis. The base pivot axes of the pair of arms are spaced apart by a separation S, and are both normal to the work axis. Preferably, the base pivot axes reside in a plane which is parallel to the work axis.
A nozzle block is provided, which is pivotably connected to each of the arm free end regions of the pair of arms so as to pivot about block pivot axes which again are spaced apart at the separation S and are normal to the work axis. The pair of arms have an effective length L which is defined as the distance between the base pivot axis and the block pivot axis of each of the arms. Employing arms with the same effective length L and so connecting the arm base end regions to the positioner base and the arm free end regions to the nozzle block assures that the arms are maintained parallel with each other during operation. As the arms are pivoted with respect to the positioner base and the nozzle block, the nozzle block is moved relative to the positioner base along an arc, while maintaining a constant orientation with respect to the work axis.
The resin nozzle is mounted to the nozzle block, and has a nozzle passage therethrough and a longitudinal nozzle axis. The nozzle passage directs the path of the resin sausage along the nozzle axis as it ejected from the resin nozzle. The resin nozzle moves in an arc with the nozzle block, and the resin nozzle is so mounted thereon that the nozzle axis maintains a parallel orientation with respect to the work axis as the arms are pivoted.
As the arms are pivoted, the resin nozzle moves between a retracted position and an extended position. In the retracted position, the arms are inclined at a minimum angle with respect to the work axis and at a minimum separation from each other, resulting in the resin nozzle being spaced away from alignment with the work axis so as to prevent interference with other elements of the rock bolter. In the extended position, the nozzle axis of the resin nozzle is substantially aligned with the work axis. When the resin nozzle is moved between the retracted and extended positions, the nozzle axis is displaced by a displacement D in a plane which contains the work axis. This condition is assured by making the plane containing the work axis and the nozzle axis normal to the pivot axes. Preferably, the arms are substantially normal to the nozzle axis of the resin nozzle when the resin nozzle is in its extended position. This facilitates the alignment of the nozzle axis with the work axis by minimizing the effect of slight translation of the resin nozzle with respect to either the bolt hole or the centralizer. When a centralizer is employed, this geometry allows the resin nozzle to approach its extended position with a substantial component of its motion being parallel to the work axis, which facilitates bringing the resin nozzle into engagement with the centralizer.
The position of the resin nozzle with respect to the other elements of the rock bolter are preferably so arranged that the nozzle passage is in close proximity to the bolt hole when the resin nozzle is in its extended position. It is preferred for the resin nozzle to be adjustably mounted to the nozzle block to allow its longitudinal position along the nozzle axis to be adjusted. When a centralizer is employed, the resin nozzle preferably engages the centralizer in the extended position.
The length L of the arms is selected to provide a sufficient displacement D that, when the resin nozzle is in its retracted position, it will not interfere with other elements of the rock bolter. Additionally, the resin nozzle positioner must be mounted with respect to the frame of the rock bolter so as to provide a clear arc in which the nozzle block and the resin nozzle can move.
The resin nozzle is preferably provided with a nozzle head which provides a reinforced structure to the end of the nozzle passage. When a centralizer is employed, the nozzle head is preferably configured to guidably engage the centralizer such that, when the resin nozzle is moved to its fully extended position, the nozzle passage of the resin nozzle is positioned adjacent to the centralizer passage of the centralizer and aligned therewith. The nozzle head is also preferably provided with a ramp surface which serves to prevent the nozzle head from becoming stuck on nearby structures when the resin nozzle is moved to its retracted position.
A flexible resin hose is connected to the resin nozzle to feed resin sausages thereto. Preferably, the flexible resin hose remains free of the remaining structure of the rock bolter to reduce the risk of entanglement or interference.
An actuator is provided, and is connected with respect to two of the following elements: the arms, the positioner base, and the nozzle block. The actuator can be connected either directly to these elements or to an element affixed to them, such as being fixed to the frame or the resin nozzle. In all cases, the actuator acts to move the arms such that the resin nozzle is moved between its retracted and extended positions.
Preferably, the actuator is a linear actuator, terminating in a first actuator end and a second actuator end, and the linear actuator can be activated to vary the separation between the first actuator end and the second actuator end. The first and second actuator ends of the linear actuator are pivotably connected as discussed above. Such linear actuators can be provided by a variety of devices known in the art such as jacks, rack and pinion mechanisms, or pneumatic or hydraulic cylinders.
In one further preferred embodiment, the first actuator end is pivotably attached to the frame of the rock bolter at a point spaced apart from the base pivot axes where the arm base end regions mount to the positioner base, and the second actuator end is pivotably attached to one of the arms at a position spaced apart from the base pivot axis. This arrangement is well suited to providing a substantial displacement D of the nozzle axis when moved between the extended and the retracted positions, while positioning the resin nozzle in close proximity to the frame in the retracted position.